Apparatus for supporting articles without structural contact and for positioning the supported articles



Aug. 11, 1970 J. c. LOGUE 3,523,706

APPARATUS FOR SUPPORTING ARTICLES WITHOUT STRUCTURAL CONTACT AND FORPOSITIONING THE SUPPORTED ARTICLES Filed Oct. 27, 196'? 2s 27 all! y. g23 -2-:

42 7 1 FIG. 3A

INVENTOR JOSEPH C. LOGUE BY M/Wr ATTORNEY United States Patent Oflice3,523,706 APPARATUS FOR SUPPORTING ARTICLES WITH- OUT STRUCTURAL CONTACTAND FOR POSI- TIONING THE SUPPORTED ARTICLES Joseph C. Logue,Poughkeepsie, N.Y., assignor to International Business MachinesCorporation, Armonk, N.Y., a corporation of New York Filed Oct. 27,1967, Ser. No. 678,704 Int. Cl. B66c 1/02 US. Cl. 294-64 7 ClaimsABSTRACT OF THE DISCLOSURE Apparatus for supporting wafer-like articleswithout structurally contacting the articles. A plate is positioned inproximate spaced relationship with a surface of the article. A flow ofair under positive pressure parallel to the plate is introduced into thespace between the surface and the plate. The article is held suspendedand spaced from the plate by the Bernoulli effect due to the reduced airpressure in the space resulting from the increased velocity of the airin said space. Projections from the plate limit lateral movement of thesupported article.

BACKGROUND OF THE INVENTION Field of invention The present inventionrelates to apparatus for handling articles by fluid dynamics. Moreparticularly it relates to apparatus for supporting and for positioningthe articles.

Description of the prior art The handling of small fragile articles suchas semiconductor wafers has presented a problem. Because of theirfragility and their susceptibility to marring, manual SUMMARY OF THEINVENTION The present invention provides apparatus for pickup and themovement of articles such as wafers without physically contacting thearticles. The apparatus comprises a plate which is operationallymaintained in proximate spaced relationship with a surface of the waferand means for introducing into the space between the wafer surface andthe plate a flow of air or other fluid under positive pressure parallelto the plate.

The fiow of air above the surface of the wafer relative to thesubstantially stable condition of the air below the wafer results in aBernoulli effect. The relatively reduced pressure above the wafer in thespace between the wafer and the plate causes the wafer to be drawntoward the plate to a position where the wafer is suspended in spacedrelationship to the plate. The retained wafer may then be moved bymoving the apparatus from one position to another. To release the wafer,the air flow is terminated.

It has been found that probably due to stray air currents, irregularmovement of the apparatus or other causes, the suspended wafer displaysa tendency to move laterally. If this lateral movement is not limited,it will cause a disruption of the parallel air flow within the spacebetween the wafer and plate resulting in the premature Patented Aug. 11,1970 release of the wafer. The apparatus of the present inventionfurther includes retaining means associated with the plate for limitingthe lateral movement of suspended wafers. Such retaining means projectfrom the plate to laterally enclose the wafer and have openings topermit the unimpeded passage of the air flow.

The air flow is preferably introduced into the space between the plateand wafer through one or more apertures in the plate.

In accordance with another aspect of the present invention, advantage istaken of the facility with which the suspended wafer may be movedlaterally and rotated. Utilizing a circular wafer having a peripheralnotch and a plate having a projection which is registrable with saidnotch, air or other suitable fluid is applied through an aperture in theplate against the surface of the wafer to move the wafer laterally ortranslationally toward the projection. Similarly, air is applied throughan aperture in the plate against the surface of the wafer to rotate thewafer. Therefore, as a result of the applied forces, the suspended wafermoves laterally until it engages the projection and then continues torotate until the notch registers with the projection to fix theorientation of the wafer. This provides apparatus for translationallyand rotationally positioning the wafer while the same is suspended onthe supporting apparatus.

Accordingly, it is a primary object of the present invention to provideapparatus for supporting and conveying articles without physicallycontacting the supported articles.

It is another object to provide apparatus for supporting and conveyingarticles without physical contact having means for preventing thepremature release of the supported article.

It is a further object to provide apparatus for supporting and conveyingarticles without physical contact having means for translationally androtationally orienting the conveyed articles.

The foregoing and other objects, features, and advantages of theinvention will be apparent from the following more particulardescription of a preferred embodiment of the invention as illustrated inthe accompanying drawings:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagrammatic plan view ofa preferred embodiment of the apparatus of this invention.

FIG. 1A is a partial sectional view taken along line 1A1A of FIG. 1.

FIG. 2 is a diagrammatic plan View of another embodiment of the presentinvention.

FIG. 2A is a sectional view taken along line 2A2A of FIG. 1.

FIG. 3 is a diagrammatic plan view of still another embodiment of theapparatus of the present invention.

FIG. 3A is a sectional view taken along line 3A3A of FIG. 3.

DESCRIPTION OF THE PREFERRED o EMBODIMENTS Referring to FIGS. 1 and 1A,wafer carrier 10 comprises housing 11 enclosing central manifold 12.Base plate 13 has formed therein apertures 14 communicating withmanifold 12 and symmetrically disposed with respect to the center ofbase plate 13. A source of the air under positive pressure is applied tomanifold 12 through conduit 17. The air is then forced from manifold 12through apertures 14 into space 15 between base plate 13 and wafer 16.This creates a stream or flow of air flowing parallel to the base plateand radially from the central portion of the plate towards the peripheryof the plate and the wafer. Because the air above wafer 16 has a steadyflow while the air below the wafer is relatively static, a Bernoullieffect is created wherein an area of reduced pressure is formed Withinspace 15. The normal or ambient air pressure below the wafer acts topush wafer 16 against this reduced pressure towards plate 13. The flowof air within space acts to prevent wafer 16 from contacting plate 13,and wafer 16 is thus retained by the carrier in suspended spacialrelationship with respect to base plate 13. By connecting suitablehandle means to tube 17, the wafer may be transferred from one locationto another by manually moving the carrier. 7

It has been found that during wafer pickup and movement, surface 18 ofwafer 16 is subjected to stray air currents which tend to push the waferlaterally. In addition, jarring and abrupt movement during conveying ofthe carrier may impart lateral motion to the wafer. If not limited, suchlateral motion will cause the wafer to reach a position where the airflow within space 15 is disrupted. This will cause a premature releaseof wafer 16. In order to limit such lateral movement, projections 19extend from plate 13 to laterally enclose the wafer. A wafer movinglaterally in any direction will shortly be stopped by one or more ofprojections 19. Where the wafer to be picked up is initially lying on aflat surface, projections 19 serve the additional purpose of acting asstandoffs to prevent plate 13 from contacting wafer surface 18 whencarrier 10 is brought into engagement with the wafer.

When the wafer is to be released from the carrier, the air feed may beterminated. More conveniently, when the carrier is handled manually, aconstant feed of air may be applied to tube 17', and the flow of airinto conduit 17 is controlled by means of vent 20. When air is to beapplied to the carrier, the operator closes vent 20 with his finger 21as shown in FIG. 1. When air flow is to be terminated so that the wafermay be released, the operators finger is removed from vent 20 permittingthe air to be vented rather than being fed to conduit 17.

In accordance with another embodiment of the present invention, lateraland rotational motion is imparted by aerodynamic means to the wafersuspended in the carrier to move the wafer into a preselected rotationaland translational orientation. Referring to FIGS. 2 and 2A, wafer 22having peripheral notch 23 formed therein is suspended on carrier 24 inthe manner described with respect to the embodiment of FIG. 1. A sourceof air under positive pressure is applied through tube 25 and conduit 26to manifold 27. Air leaving manifold 27 through central aperture 28 inbase plate 29 provides the air flow in intermediate space 30 parallel tothe base plate 29 which creates the area of reduced pressure in space 30necessary to retain wafer 22 in suspended spaced relationship in respectto plate 29. Orienting stud 31 projects from base plate 29. Peripheralnotch 23 in wafer 22 is registrable with stud 31, and when the notch isso registered, the wafer is in the preselected rotational andtranslational orientation. In order to move notch 23 into registrationwith stud 31, apertures 32 and 33 are formed in base plate 29 at such anangle that air forced from manifold 27 through these apertures impingesagainst surface 34 of wafer 22 to impart to said wafer a lateral motiontoward stud 31. In a similar manner, air forced from manifold 27 throughapertures 35 and 36 in base plate 29 impinges against wafer surface 34in the direction shown in FIG. 2 to impart a resultant rotational motionto wafer 22. Therefore, wafer 22 while suspended is moved laterallyuntil its periphery contacts stud 31. The wafer continues to rotatewhile in contact with stud 31 until notch 23 registers with stud 31. Thewafer is then retained on the carrier in the preselected translationaland rotational orientation. The oriented wafer may then be released inthe manner described with respect to the embodiment of FIG. 1.

Retaining wall 38 projecting from base plate 29 laterally encloses wafer22 and acts to limit any of the previously described stray or randomlateral movements of 4 wafer 22. Apertures 39 formed in wall 38 permitunimpeded air flow passage through the retaining wall.

While the embodiment of FIG. 2 discloses a structure in which theparallel or suspending air flow, the air stream for translationallymoving the wafer, and the air streams for rotationally moving the waferare applied through individual apertures, it is possible to provide astructure in which the three motions are imparted to the wafer by meansof air emitted from a single aperture. The embodiment shown in FIGS. 3and 3A discloses such a structure. By utilizing in the carrier a conduit40 emitting air at an angle sufiicient to impart to the surface of wafer37 a translational movement towards stud 42 and which has an opening 41off-center with respect to the plate so that the emitted air imparts arotational movement to the wafer, all three functions are performedsince a substantial portion of air leaving aperture 41 still forms anair flow within space 43 between the wafer and base plate 44 to providethe area of reduced pressure necessary to suspend the wafer.

In the manner previously described, the suspended wafer will be movedtranslationally into contact with stud 42 while continuing to rotateuntil notch 45 registers with the stud to orient the wafer. Retainingwall 46 having apertures 47 performs the previously described func tionof limiting any stray or random lateral movements of wafer 37.

While the specific embodiments have been described utilizing air, itshould be clear that the fluid dynamic principles involved in thepresent invention would apply irrespective of the nature of the fluidused. Both gases and liquid may be utilized. However, it is preferablethat the fluid which is applied under positive pressure be in the samestate as the ambient or the medium through which the wafer is to becarried.

While the invention has been particularly shown and described withreference to preferred embodiments thereof, it will be understood bythose skilled in the art that various changes in form and detail may bemade therein without departing from the spirit and scope of theinvention.

What is claimed is:

1. Apparatus for positioning and supporting a circular wafer having aperipheral notch in a preselected rotational and translationalorientation without physically contacting a surface of said wafercomprising a flat plate in proximate, spaced relationship with a surfaceof said wafer said plate having formed therein at least one aperture asource of fluid under positive pressure in the same state as the ambientconnected to said at least one aperture for introducing through saidaperture into the space between the wafer and the plate a flow of saidfluid parallel to the plate to suspend said wafer in spaced relationshipto said plate a projection from said plate adapted to be registrablewith said wafer notch means for applying fluid through said at least oneaperture gainst the surface of the wafer to move the wafertranslationally toward said projection, and means for applying fluidthrough said at least one aperture against the surface of said water torotate said wafer, whereby the wafer engages the projection and rotatesuntil the notch registers with the projection to fix the orientation ofthe wafer.

2. The apparatus of claim 1 wherein said fl-uid is gas.

3. The apparatus of claim 2 wherein said plate has one aperture formedtherein.

4. The apparatus of claim 2 wherein said source of gas and both of saidmeans for applying gas are connected to the same aperture.

5. The apparatus of claim 2 wherein said source of gas and both of saidmeans for applying gas are connected to individual apertures.

6. The apparatus of claim 2 further including retaining means extendingfrom the plate to laterally enclose the supported article, saidretaining means having openings to permit the passage of gastherethrough.

7. The apparatus of claim 6 wherein said projection is positionedintermediate the wafer periphery and the retaining means.

References Cited UNITED STATES PATENTS 3,425,736 2/1969 Benjamin 294-646 Tarbuck.

Walton et a1. 271--26 Misson.

Williams 271-26 FOREIGN PATENTS Great Britain.

ANDRES H. NIELSEN, Primary Examiner

